Undertaken at the request of the U.S. Employment Service (USES), this study assesses the validity and fairness of the General Aptitude Test Battery (GATB). The U.S. Department of Labor is considering whether to promote the use of the GATB throughout the USES to screen many of the 19 million persons passing through the system annually in search of private- and public-sector jobs. Topics addressed include the policy context, issues in equity and law, the role of the USES, psychometric properties and other characteristics of the GATB, problems affecting the GATB (test administration, speededness, and coachability), the theory of validity generalization, application of validity generalization to the GATB, differential validity and differential prediction, assessment of the USES's GATB referral service, and evaluation of economic claims associated with the referral service. The report concludes with recommendations for referral and score reporting. A synthesis of research on the psychometrics of the GATB, tables summarizing GATB reliabilities, and biographical sketches of committee members contributing to the report are appended. (TJH)